Project Summary/Abstract This proposal describes a four-year career development plan designed to lead the PI to a career as an independent clinician scientist studying the mechanisms of emotional vulnerability after severe medical illness. More than one third of critical illness survivors suffer long term from depression, anxiety, or post-traumatic stress disorder. Animal research on this topic is scarce, but is necessary in order to better understand the mechanisms of vulnerability and to identify targets for intervention. The long-term goal of this research is to identify the molecular mechanisms and neural circuitry behind emotional vulnerability after severe medical illness, and to translate this knowledge into effective strategies for the prevention and treatment of psychiatric disorders in critical illness survivors. Preliminary studies using a murine sepsis model, cecal ligation and puncture (CLP), showed increased anxiety-like behavior in CLP survivor mice, and in situ hybridization studies suggested a possible role for the ventral hippocampus. In the first Specific Aim, the candidate will investigate the role of the ventral hippocampus in anxiety-like behavior after CLP by examining the activity of ventral CA1 pyramidal cells after CLP using in vivo calcium imaging, and determining the effect of optogenetic activation of the ventral hippocampus on anxiety-like behavior. Studies of patients after traumatic experiences including critical illness have suggested that elevated circulating glucocorticoids during trauma may protect against post-traumatic stress symptoms in survivors. In the second Specific Aim, the candidate will investigate whether glucocorticoid treatment during the illness period can protect against negative emotional behavior in CLP survivors, and use RNA-seq to identify candidate genes that could mediate the effects of CLP and glucocorticoids on ventral hippocampal function and emotional behavior. The applicant holds M.D. and Ph.D. degrees and has completed clinical specialty training in Internal Medicine and Endocrinology. She has previous experience in behavioral endocrinology research using mouse models. This application includes a career development plan designed to update her scientific skills in techniques for investigating the neural circuits of behavior in awake, freely behaving animals, and in the design and analysis of large-scale gene expression data. The training will include didactic training, conferences and lab meetings, hands-on apprenticeship, and the communication of research findings through publications and presentation at national meetings. The mentorship team includes members of multiple departments/divisions and multiple institutions, in order to support this inherently interdisciplinary project. The mentors are able to provide a research environment with adequate resources to complete the proposed project.